Possible causes for "tuple concurrently updated" error

Hi,

I'm seeing a "tuple concurrently updated" error thrown while executing
UPDATE statements. I've attempted to diligently review previous threads on
this error (e.g.,
https://www.google.com/webhp?ie=UTF-8#q=tuple+concurrently+updated+update+site:postgresql.org)
but am confused about what classes of queries can conflict to cause this
error.

- It seems clear from previous threads that
- two concurrent ANALYZE queries on the same table can cause this
this error.
- some access control/DDL statements (e.g. GRANT) run concurrently
can cause this error.
- Can a "VACUUM ANALYZE $TABLE" (e.g., from autovacuum) concurrent with
a "UPDATE $TABLE" cause this error?
- Can two concurrent "UPDATE $TABLE" queries which touch completely
disjoint sets of rows (e.g. where clause on primary key with disjoint
filters) cause this error?

Thanks,

Jacob